From 2edb12e249387a72b24f5f34efae4735d589af9f Mon Sep 17 00:00:00 2001
From: Jack Lloyd <jack@randombit.net>
Date: Fri, 29 Sep 2017 19:15:48 -0400
Subject: In secure_allocator, hide mlock/new usage in a function in mem_ops

Switch to calloc/free instead of new/delete - shouldn't matter since
we are only allocate integral types.

This change reduces the size of libbotan-2.so by ~300 Kb on my system.
---
 .../utils/locking_allocator/locking_allocator.cpp  |  2 +-
 .../utils/locking_allocator/locking_allocator.h    |  2 +-
 src/lib/utils/mem_ops.cpp                          | 32 ++++++++++++++++++++++
 src/lib/utils/mem_ops.h                            | 18 ++++++++++++
 4 files changed, 52 insertions(+), 2 deletions(-)

(limited to 'src/lib/utils')

diff --git a/src/lib/utils/locking_allocator/locking_allocator.cpp b/src/lib/utils/locking_allocator/locking_allocator.cpp
index 880f3add8..f36fa9130 100644
--- a/src/lib/utils/locking_allocator/locking_allocator.cpp
+++ b/src/lib/utils/locking_allocator/locking_allocator.cpp
@@ -116,7 +116,7 @@ void* mlock_allocator::allocate(size_t num_elems, size_t elem_size)
    return nullptr;
    }
 
-bool mlock_allocator::deallocate(void* p, size_t num_elems, size_t elem_size)
+bool mlock_allocator::deallocate(void* p, size_t num_elems, size_t elem_size) BOTAN_NOEXCEPT
    {
    if(!m_pool)
       return false;
diff --git a/src/lib/utils/locking_allocator/locking_allocator.h b/src/lib/utils/locking_allocator/locking_allocator.h
index 8e38129e2..e9299c120 100644
--- a/src/lib/utils/locking_allocator/locking_allocator.h
+++ b/src/lib/utils/locking_allocator/locking_allocator.h
@@ -21,7 +21,7 @@ class BOTAN_PUBLIC_API(2,0) mlock_allocator final
 
       void* allocate(size_t num_elems, size_t elem_size);
 
-      bool deallocate(void* p, size_t num_elems, size_t elem_size);
+      bool deallocate(void* p, size_t num_elems, size_t elem_size) BOTAN_NOEXCEPT;
 
       mlock_allocator(const mlock_allocator&) = delete;
 
diff --git a/src/lib/utils/mem_ops.cpp b/src/lib/utils/mem_ops.cpp
index 45de24cb8..b2097e4c7 100644
--- a/src/lib/utils/mem_ops.cpp
+++ b/src/lib/utils/mem_ops.cpp
@@ -6,8 +6,40 @@
 
 #include <botan/mem_ops.h>
 
+#if defined(BOTAN_HAS_LOCKING_ALLOCATOR)
+  #include <botan/locking_allocator.h>
+#endif
+
 namespace Botan {
 
+void* allocate_memory(size_t elems, size_t elem_size)
+   {
+#if defined(BOTAN_HAS_LOCKING_ALLOCATOR)
+   if(void* p = mlock_allocator::instance().allocate(elems, elem_size))
+      return p;
+#endif
+
+   void* ptr = std::calloc(elems, elem_size);
+   if(!ptr)
+      throw std::bad_alloc();
+   return ptr;
+   }
+
+void deallocate_memory(void* p, size_t elems, size_t elem_size)
+   {
+   if(p == nullptr)
+      return;
+
+   secure_scrub_memory(p, elems * elem_size);
+
+#if defined(BOTAN_HAS_LOCKING_ALLOCATOR)
+   if(mlock_allocator::instance().deallocate(p, elems, elem_size))
+      return;
+#endif
+
+   std::free(p);
+   }
+
 bool constant_time_compare(const uint8_t x[],
                            const uint8_t y[],
                            size_t len)
diff --git a/src/lib/utils/mem_ops.h b/src/lib/utils/mem_ops.h
index 328196000..4b03b23d2 100644
--- a/src/lib/utils/mem_ops.h
+++ b/src/lib/utils/mem_ops.h
@@ -14,6 +14,24 @@
 
 namespace Botan {
 
+/**
+* Allocate a memory buffer by some method. This should only be used for
+* primitive types (uint8_t, uint32_t, etc).
+*
+* @param elems the number of elements
+* @param elem_size the size of each element
+* @return pointer to allocated and zeroed memory, or throw std::bad_alloc on failure
+*/
+BOTAN_PUBLIC_API(2,3) void* allocate_memory(size_t elems, size_t elem_size);
+
+/**
+* Free a pointer returned by allocate_memory
+* @param p the pointer returned by allocate_memory
+* @param elems the number of elements, as passed to allocate_memory
+* @param elem_size the size of each element, as passed to allocate_memory
+*/
+BOTAN_PUBLIC_API(2,3) void deallocate_memory(void* p, size_t elems, size_t elem_size);
+
 /**
 * Scrub memory contents in a way that a compiler should not elide,
 * using some system specific technique. Note that this function might
-- 
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